1. Field of the Invention
The present invention relates to an image display device by which an optical image signal based on image information is projected onto a display means to display an image, and a method for adjusting optical elements of in the image display device into alignment.
2. Description of the Prior Art
FIG. 95 is a diagrammatic representation of a conventional image display device. Reference numeral 1 denotes a luminous element for emitting light; 2 denotes a parabolic reflector for reflecting the light from the luminous element 1 mostly into parallel rays of light; and 3 denotes a condenser lens for gathering the light reflected by the parabolic reflector 2. The luminous element 1, the parabolic reflector 2 and the condenser lens 3 constitute an illumination light source system.
Reference numeral 4 denotes a light valve for spatially intensity-modulating the light gathered by condenser lens 3 based on image information; 5 denotes a projecting optical lens for projecting the light intensity-modulated by the light valve onto a screen; and 6 denotes the screen for displaying, as an image, the light projected thereon by the projecting optical lens 5. The arrows indicate optical paths.
Next, the operation of the prior art example will be described below.
Light emitted from the luminous element 1 is reflected by the parabolic reflector 2 and focused through the condenser lens 3 onto the light valve 4. The light valve 4 spatially intensity-modulates the focused light based on image information. The intensity-modulated light is projected by the projecting optical lens 5 onto the screen 6 from behind (from the left-hand side in FIG. 95) and displayed thereon. A user of the image display device visually identifies the image from the front (from the right-hand side in FIG. 95).
The depth dimension of the image display device of FIG. 95 corresponds to the distance from the illumination light source system composed of the luminous element 1, the parabolic reflector 2 and the condenser lens 3 to the screen 6. It is preferable to minimize the depth dimension of the image display device if the image size displayable is the same. For such a reason, the conventional image display device of FIG. 95 uses a wide-angle projecting optical lens 5 to display an image on the screen so that the depth dimension of the display device is minimized to provide a flat device configuration.
Since the projecting optical lens 5 has a limitation of increasing its angle of field, however, it is customary in the art, with a view to reducing the depth dimension, to place a plane mirror at an angle of 45xc2x0 to the horizontal to bend the optical path from the projecting optical lens 5, projecting an image onto the screen 6 as depicted in FIG. 96.
In the image display device of FIG. 96, the illumination light source system, the light valve 4 and the projecting optical lens 5 are disposed in the direction of height of the device (in the vertical direction in FIG. 96) to reduce the depth dimension of the device. The depth dimension of the image display device in this case corresponds to the distance from the plane mirror 7 to the screen 6. With the plane mirror 7 tilted more than 45xc2x0 from the horizon, the depth dimension of the image display device can be further reduced; in this instance, however, the light valve 4 and the illumination light source system interfere with the projected light, and the light is shaded or eclipsed accordingly, resulting in the light path getting out of the screen 6.
In Japanese Patent Application Laid-Open Gazette 6-11767 there is disclosed an image display device of the type wherein light is reflected by a convex mirror is used in place of the plane mirror 7 in FIG. 96 to display a magnified image on the screen 6, but the image displayed on the screen 6 is distorted.
The conventional device configurations described above impose limitations on the reduction of the depth dimension of the device and permit no further reduction.
It is therefore an object of the present invention to provide an image display device that provides an enlarged display of distortion-free images and permits further reduction of its depth dimension than in the prior art.
Another object of the present invention is to provide a method of adjusting optical elements of the image display device into alignment.
According to an aspect of the present invention, there is provided an image display device which comprises projecting optical means composed of a reflecting part for reflecting the optical image signal, and a refracting optical part for correcting for a distortion if the reflecting part has the distortion and for projecting the optical image signal onto the reflecting part, and wherein display means receives the optical image signal through the projecting optical means.
According to another aspect of the present invention, there is provided an image display device which comprises projecting optical means composed of a reflecting part having a reflecting surface for reflecting the optical image signal, and a refracting optical part having a refracting surface for projecting the optical image signal onto the reflecting part, and wherein the display means receives the optical image signal through the projecting optical means and at least one of the reflecting surface and the refracting surface is aspherical.
According to another aspect of the present invention, the transmitting means comprises: an illumination light source part for emitting illumination light; and a reflecting type image information providing part for receiving the illumination light emitted from the illumination light source part and for providing image information to the illumination light and reflecting the illumination light as the optical image signal.
According to another aspect of the present invention, the reflecting part has a rotationally symmetric aspherical surface for reflecting the optical image signal transmitted from the transmitting means.
According to another aspect of the present invention, the reflecting part is a convex mirror of negative power.
According to another aspect of the present invention, the reflecting part is a Fresnel mirror of negative power.
According to another aspect of the present invention, the reflecting part has a reflecting surface that is formed by a low dispersive medium and a high dispersive medium stacked in the direction in which to transmit the optical image signal sent from the transmitting means, has a negative power and reflects the optical image signal having passed through the low and high dispersive media.
According to another aspect of the present invention, the reflecting part has a reflecting surface formed so that its convex curvature is large around an optical axis and becomes smaller toward the periphery of the reflecting surface.
According to another aspect of the present invention, the reflecting part has an odd-order aspherical reflecting surface obtained by adding odd-order terms to a polynomial composed of even-order terms.
According to another aspect of the present invention, the refracting optical part has odd-order aspherical refracting surfaces obtained by adding odd-order terms to a polynomial composed of even-order terms.
According to another aspect of the present invention, the reflecting part or refracting optical part reflects or refracts the optical image signal by the reflecting or refracting surface except around the optical axis of the reflecting or refracting part.
According to another aspect of the present invention, the refracting optical part is provided with a curvature-of-field correcting means for canceling a curvature of field of the reflecting part.
According to another aspect of the present invention, the refracting optical part is provided with positive lenses of positive power, negative lenses of negative power having a refractive index lower than that of the positive lens, and a Petzval""s sum correcting lens for correcting for a Petzval""s sum contributing component of reflecting part.
According to another aspect of the present invention, the projecting optical means has an aspherical optical surface at places where principal rays of the optical image signal to be projected onto the reflecting part from the transmitting means are divergent and/or convergent.
According to another aspect of the present invention, the projecting optical means is provided with path-bending means for reflecting the optical image signal from the refracting optical part to the reflecting part, the optical axis of the refracting optical part being bent at an appropriate angle in a horizontal plane containing the optical axis of the reflecting part.
According to another aspect of the present invention, the projecting optical means is provided with path-bending means for reflecting the optical image signal from first lens means to second lens means.
According to another aspect of the present invention, the refracting optical part has at least one lens formed of synthetic resin.
According to another aspect of he present invention, the refracting optical part and the reflecting part are rotationally symmetric about an optical axis made common to them.
According to another aspect of the present invention, the image display device further comprises a plane mirror for reflecting the optical signal from the projecting optical means to the display means.
According to another aspect of the present invention, a light receiving surface of display means and a reflecting surface of plane mirror are held in parallel to each other.
According to another aspect of the present invention, the refracting optical part comprises a retro-focus optical system composed of a positive lens group of positive power and a negative lens group of negative power, and a refracting optical lens for fine-tuning the angle of emission of the optical image signal from the retro-focus optical system to the reflecting part.
According to another aspect of the present invention, the retro-focus optical system is composed of two positive lens groups and one negative lens group.
According to another aspect of the present invention, the retro-focus optical system is composed of one positive lens group and one negative lens group.
According to another aspect of the present invention, the refracting optical part comprises negative lenses having an average value of refractive indexes in the range of 1.45 to 1.722 and having negative power, and positive lenses having an average value of refractive indexes in the range of 1.722 to 1.9 and having positive power.
According to another aspect of the present invention, the refracting optical part comprises negative lenses having an average value of Abbe""s number in the range of 25 to 38 and having negative power, and positive lenses having an average value of Abbe""s number in the range of 38 to 60 and having positive power.
According to another aspect of the present invention, the refracting optical part comprises positive lenses made of glass materials and negative lenses made of glass materials, the difference between average refractive indexes of the glass materials for the positive and negative lenses is in the range of 0.04 to 1.
According to another aspect of the present invention, the refracting optical part comprises positive lenses made of glass materials and negative lenses made of glass materials, the difference between average Abbe""s number of the glass materials for the positive and negative lenses is in the range of 0 to 16.
According to another aspect of the present invention, a back focal length from the closest one of a plurality of lenses forming the refracting optical part to a light emitting surface of the transmitting means to the light emitting surface is equal to the distance from the light emitting surface of the transmitting means to the position of an entrance pupil of the refracting optical part.
According to another aspect of the present invention, the projecting optical means has negative lenses of negative power provided at the position of low marginal ray.
According to another aspect of the present invention, the angle of bending the optical axis of the refracting optical part is set such that the refracting optical part is as close to a path from the path-bending means to the reflecting part as possible without intercepting the optical path.
According to another aspect of the present invention, the angle of bending the optical axis of the first lens means is set such that the first lens means is as close to a path from the path-bending means to the second lens means as possible without intercepting the optical path.
According to another aspect of the present invention, the shortest distance from the refracting optical part to a reflecting part placement plane is chosen within a range smaller than a thickness limiting value.
According to another aspect of the present invention, the longer one of the longest distance from a reflecting part placement plane to the path-bending means and the longest distance from the reflecting part placement plane to the refracting optical part is equal to a thickness limiting value.
According to another aspect of the present invention, the longest distance from a reflecting part placement plane to the path-bending means and the longest distance from the reflecting part placement plane to the refracting optical part are equal to each other.
According to another aspect of the present invention, the refracting optical part has a shape obtained by removing a non-transmitting portion that does not transmit the optical image signal.
According to another aspect of the present invention, the reflecting part has a shape obtained by removing a non-reflecting portion that does not reflect the optical image signal to the display means.
According to another aspect of the present invention, the image display device further comprises a retaining mechanism for retaining the refracting optical part and the reflecting part as a one-piece structure.
According to another aspect of the present invention, the image display device further comprises a retaining mechanism for retaining the refracting optical part, the path-bending means and the reflecting part as a one-piece structure.
According to another aspect of the present invention, the refracting optical part has positive lenses of positive power provided at the position of high marginal ray.
According to another aspect of the present invention, letting hi represent the height of the marginal ray of light incident to the refracting optical part, hm the maximum height of the marginal ray in a positive lens disposed at the center of the refracting optical part and ho represent the height of the marginal ray of light emitted from the refracting optical part, the refracting optical part satisfy the relationships 1.05hi less than hm less than 3hi and 0.3hi less than ho less than 1hi.
According to another aspect of the present invention, the projecting optical means has poor optical performance in an unused area around its optical axis but has high image formation performance in an area to be used other than that around the optical axis.
According to another aspect of the present invention, the projecting optical means is adapted so that an image-forming position at the center of the optical axis and an image-forming position around the optical axis are not in the same plane.
According to another aspect of the present invention, the projecting optical means allows distortion in the vicinity of the center of the optical axis to increase the image formation performance of the area to be used.
According to another aspect of the present invention, the projecting optical means limits the range of degradation of the optical performance to the range of the field angle related only to the base of a screen.
According to another aspect of the present invention, a plane mirror for reflecting the light from the projecting optical means to the display means has a shape that corrects for distortion of the projecting optical means.
According to another aspect of the present invention, the refracting optical part has a construction in which an exit pupil of light emitted toward the central area of the reflecting part around the optical axis thereof and an exit pupil of light emitted toward the peripheral area of the reflecting part are spaced apart to thereby adjust the position and angle of incidence of the emitted light, toward the reflecting part.
According to another aspect of the present invention, the reflecting part has a uniform thickness from its front surface as a reflecting surface for reflecting the optical image signal to the rear surface provided behind the front surface.
According to another aspect of the present invention, the reflecting part has a planar low-reflectivity surface provided on a non-projecting front surface about the optical axis of the reflecting part and a planar high-reflectivity surface smaller in area than the low-reflectivity surface and provided in the low-reflectivity surface about the optical axis.
According to another aspect of the present invention, the transmitting means is provided with a cover glass for protecting an image information light emitting surface and a compensator glass of an optical thickness that decreases or increases as a change in the optical thickness of the cover glass increases or decreases, the transmitting means emitting the image information light to the refracting optical part through the cover glass and the compensator glass.
According to another aspect of the present invention, the refracting optical part is provided with means for detachably mounting the compensator glass on the side of incidence of the illumination light from the transmitting means.
According to another aspect of the present invention, the image display device further comprises a bottom perpendicular to the reflecting surface of the plane mirror and the light receiving surface of the display means, and an optical component is disposed in a space defined by segments joining: a first point present on the base of a square image displayed on the display means and the farthest from the center of the image; a second point on the plane mirror to which light toward the first point is reflected; a third point on the reflecting part to which light toward the second point is reflected; a first projected point by projecting the first point to the bottom from the direction normal to the bottom; a second projected point by projecting the second point to the bottom from the direction normal to the bottom; and a third projected point by projecting the third point from the direction normal to the bottom.
According to another aspect of the present invention, the transmitting means comprises: a converging optical system principal part composed of: an illumination light source part for emitting illumination light; a color wheel for coloring emitted light from the illumination light source part in three primary colors one after another; a rod integrator for receiving the illumination light from the illumination light source part and for emitting illumination light of a uniform illuminance distribution from a light emitting surface; and a relay lens for relaying the illumination light from the rod integrator; a field lens for directing principal rays of the illumination light from the relay lens to the same direction; and a reflecting type image information providing part for providing image information to the illumination light from the field lens. The converging optical system principal part is disposed as the optical component in the space, and is further provided with second and third path-bending means for reflecting the illumination light from the converging optical system principal part to the field lens.
According to another aspect of the present invention, the optical axis of the converging optical system principal part is parallel to the light receiving surface of the display means and the bottom.
According to another aspect of the present invention, the optical axis of the converging optical system principal part is parallel to the light receiving surface of the display means and is tilted so that the intersection point of the illumination light source part and the optical axis is higher than the intersection point of the relay lens and the optical axis in the vertical direction.
According to another aspect of the present invention, the transmitting means is provided with an adjustment table for mounting the converging optical system principal part and the field lens, the adjustment table having a hole for receiving the third path-bending means.
According to another aspect of the present invention, at least one of the second and third path-bending means has a curved optical surface.
According to another aspect of the present invention, the reflecting part is made of synthetic resin.
According to another aspect of the present invention, the reflecting part is rectangular in front configuration viewed form the direction of its optical axis, a nonreflecting portion of the reflecting part that does not reflect the optical image signal to the display means being removed. The reflecting part is provided with: a first screwing part provided on the lower side of the rectangular front configuration close to but spaced a predetermined eccentric distance apart from the optical axis of the reflecting part and pivotally secured to a first reflecting part mounting mechanism; a second screwing part provided on another side of the rectangular front configuration and slidably held on a second reflecting part mounting mechanism; and a third screwing part provided still another side of the rectangular front configuration and slidably secured to a third reflecting part mounting mechanism.
According to another aspect of the present invention, the first reflecting part mounting mechanism and said first screwing part are screwed together by a taper screw and each have a screw hole conforming to a tapered portion of said taper screw.
According to another aspect of the present invention, the reflecting part is rectangular in front configuration viewed form the direction of its optical axis, a nonreflecting portion of the reflecting part that does not reflect the optical image signal to the display means being removed. The reflecting part is provided with: a recess provided on the lower side of the rectangular front configuration close to but spaced a predetermined eccentric distance apart from the optical axis of the reflecting part; a cylindrical support for engagement with the recess; two springs fixed at one end to the reflecting part on both sides of the recess, for biasing the reflecting part; a second screwing part provided on another side of the rectangular front configuration and slidably held on a second reflecting part mounting mechanism; and a third screwing part provided still another side of the rectangular front configuration and slidably secured to a third reflecting part mounting mechanism.
According to another aspect of the present invention, the reflecting part is rectangular in front configuration viewed form the direction of its optical axis, a nonreflecting portion of the reflecting part that does not reflect the optical image signal to the display means being removed. The reflecting part is provided with: protrusion provided on the lower side of the rectangular front configuration close to but spaced a predetermined eccentric distance apart from the optical axis of the reflecting part; a V-grooved support having a V-shaped groove for engagement with the protrusion; two springs fixed at one end to the reflecting part on both sides of the protrusion, for biasing the reflecting part; a second screwing part provided on another side of the rectangular front configuration and slidably held on a second reflecting part mounting mechanism; and a third screwing part provided still another side of the rectangular front configuration and slidably secured to a third reflecting part mounting mechanism.
According to another aspect of the present invention, the reflecting part is provided with two springs fixed at one end to the reflecting part on both sides of the first screwing part and at the other end to a common point, for biasing the reflecting part.
According to another aspect of the present invention, the first, second and third screwing parts hold the reflecting part with its reflecting front surface in contact with the first, second and third reflecting part mounting mechanisms.
According to another aspect of the present invention, the image display device further comprises: two sliding supports mounted on the retaining mechanism, for slidably supporting all or some of lenses of the refracting optical part; a first mounting plate disposed between the two sliding support and fixed to the retaining mechanism; a second mounting plate disposed between the two sliding supports and fixed to the lower ends of all or some of the lenses of the refracting optical part; and a piezoelectric element held between the first and second mounting plates and expanding or contracting in the direction of the optical axis of the refracting optical part as a control voltage applied to the piezoelectric element increases or decreases.
According to another aspect of the present invention, the image display device further comprises a gear mechanism supported on a gear support provided on the retaining mechanism, for moving the reflecting part, or all or some of lenses of the refracting optical part in the direction of the optical axis of the refracting optical part.
According to another aspect of the present invention, the image display device further comprises a heater/cooler for heating/cooling at least one of the refracting optical part held on the retaining mechanism and the retaining mechanism.
According to another aspect of the present invention, the image display device further comprises: a temperature sensor for sensing a lens-barrel temperature of the refracting optical part; a temperature sensor for sensing the internal temperature of the retaining mechanism; and a control unit for controlling at least one of the piezoelectric element, the gear mechanism and the heater/cooler according to a focus-compensation amount calculated from the lens-barrel temperature and the internal temperature.
According to another aspect of the present invention, the image display device further comprises: a temperature sensor for sensing an environmental temperature; and a control unit for controlling at least one of the piezoelectric element, the gear mechanism and the heater/cooler according to a focus-compensation amount calculated by adding the environmental temperature to a linear interpolation equation derived from at least two different focus adjustment points.
According to another aspect of the present invention, the image display device further comprises: a CCD for detecting focus information from light to be incident to a non-image-display area of the display means; and a control unit for controlling at least one of the piezoelectric element, the gear mechanism and the heater/cooler according to the result of analysis of the focus information.
According to another aspect of the present invention, the image display device further comprises a miniature reflector for reflecting to the CCD the light to be incident to the non-image-display area of the display means.
According to another aspect of the present invention, the control unit regards the intensity distribution of the light received by the CCD as focus information, analyzes a peak value of the focus information and effects control to increase the peak value.
According to another aspect of the present invention, the control unit regards the intensity distribution of the light received by the CCD as focus information, analyzes the width of a predetermined level of the focus information and effects control to decrease the width of the predetermined level.
According to another aspect of the present invention, the control unit regards the intensity distribution of the light received by the CCD as focus information, analyzes the inclination of a shoulder of the focus information and effects control to increase the inclination.
According to another aspect of the present invention, the retaining mechanism is provided with a plurality of supports for supporting the refracting optical part and the reflecting part, the plurality of supports having the same product of their height and coefficient of linear expansion.
According to another aspect of the present invention, the reflecting part has a high- or low-reflectivity surface, or a reflecting protrusion or reflecting recess that is high-reflectivity over the entire area of its reflecting surface.
According to another aspect of the present invention, the reflecting part has a lens layer covering its front surface for reflecting said optical image signal.
According to another aspect of the present invention, there is provided an image display device comprising: a cabinet front portion provided on the bottom of a cabinet and having display means; a cabinet rear portion provided on the bottom; and upper slanting surface, a left-hand slanting surface and right-hand slanting surface provided between the cabinet front portion and the cabinet rear portion and defining a housing space together with the bottom. The left- and right-hand slanting surfaces leave left- and right-hand parallel surfaces parallel to the display means on the back of the cabinet front portion and perpendicular surface perpendicular to the display means on both side of the cabinet rear portion.
According to another aspect of the present invention, the image display device further comprises a connector having a first end face for connection with either one of the left- and right-hand parallel surfaces, a second end face for connection to that one of the perpendicular surfaces on the same side of either one of the parallel surfaces, and a connection face parallel to the second end face. The connection surface is coupled to a connection face of another connector.
According to another aspect of the present invention, the connector has the same height as that of the image display device and is provided with a third end face perpendicular to the first and second end faces, for connection to the another connector.
According to another aspect of the present invention, air and heat are discharged or cables are extended out of the cabinet through the upper, left- and right-hand slanting surfaces.
According to another aspect of the present invention, there is provided a method of adjustment for correct alignment, which comprises the steps of: applying rectilinearly propagating light to a reflecting part and adjusting the attitude of the reflecting part so that the outgoing path of said rectilinearly propagating light for incidence to a high-reflectivity surface of the reflecting part and the incoming path of the rectilinearly propagating light reflected by the high-reflectivity surface come into alignment with each other; and applying the rectilinearly propagating light on the outgoing path to the high-reflectivity surface of the reflecting part through the refracting optical part, emitting from the refracting optical part therectilinearly propagating light on the incoming path reflected by the high-reflectivity surface and adjusting the attitude of the refracting optical part to maximize the power of the rectilinearly propagating light emitted from the refracting optical part.
According to still another aspect of the present invention, there is provided a method of adjustment for correct alignment, which comprises the steps of: reflecting a bundle of parallel rays, applied perpendicularly to a jig display means and having passed through a first through hole, by a high-reflectivity surface of a reflecting part to bring outgoing and incoming paths of a bundle of parallel rays into alignment between the high-reflectivity surface and the first through hole; reflecting a bundle of parallel rays about an ideal optical axis of a refracting optical part by a path-bending reflector to the high-reflectivity surface to bring outgoing and incoming paths of the bundle of parallel rays into alignment between the high-reflectivity surface and the path-bending reflector; mounting, on a lens-holding flange, a holed reflector having a second through hole made in alignment with the optical axis of the refracting optical part, and reflecting a bundle of parallel rays about an ideal optical axis of the refracting optical part by the path-bending reflector to the high-reflectivity reflector through the second through hole, by which the direction of travel of the bundle of parallel ray reflected by the holed reflector and the direction of travel of the bundle of parallel rays on an incoming path reflected by the high-reflectivity surface to the path-bending reflector are brought into coincidence with each other; removing the holed reflector from thie lens-holding flange and placing the refracting optical part on the lens-holding flange instead; and placing an illumination light source part and an image information providing part at predetermined positions, rendering the illumination light from the illumination light source part by the image information providing part to an optical image signal, and applying the optical image signal via the refracting optical part, the path-bending reflector and the reflecting part to the jig display means to form an image of the optical image signal on the jig display means at a normal position.